Method of covulcanizing chlorinated low unsaturation rubbers with high unsaturation rubber

ABSTRACT

Disclosed are chlorinated low unsaturation rubbers exhibiting improved adhesion properties and improved covulcanization ability with high unsaturation rubbers. Also disclosed is a method of preparing these rubbers which comprises reacting the chlorinated rubber with certain bromine and/or iodine containing compounds.

This is a division of application Ser. No. 537,857, filed Jan. 2, 1975,now U.S. Pat. No. 3,985,832.

BACKGROUND OF THE INVENTION

This invention relates to chlorinated low unsaturation rubbers havingboth improved adhesion properties and also improved covulcanizabilitywith high unsaturation rubbers and a method for making same.

Chlorobutyl rubber possesses many desirable properties such asexceptionally good air impermeability, flex properties and especiallygood heat resistance and aging properties. The commercial success ofchlorobutyl rubber is largely dependent on its application in suchthings as tire innerliners and sidewalls, conveyor or power transmissionbelting, steam hoses, wire insulation, etc. Chlorobutyl rubber hasproved to be useful in applications inaccessible to butyl rubber owingto the fact that the chlorinated sites of chlorobutyl enhancecovulcanization of chlorobutyl with high unsaturation rubbers. Even withthis improved covulcanization, it has long been recognized that thedegree of covulcanization of chlorobutyl with high unsaturation rubberwas not complete enough to allow for the use of chlorobutyl with highunsaturation rubber in all of the applications where its desirableproperties would be advantageous. The properties which had to beimproved before chlorobutyl could be effectively covulcanized withcertain high unsaturation rubber for such uses as high performance tireinnerliners and sidewalls were (1) the adhesion of chlorobutylvulcanizates to high unsaturation rubber vulcanizates, and (2) improvedtensile strength and dynamic stability of covulcanizates of chlorobutylwith high unsaturation rubber.

It has long been known in the art that the adhesion of chlorobutyl tohigh unsaturation rubber could be improved by the addition of smallamounts of bromobutyl rubber to chlorobutyl rubber. Such a technique isdisclosed in U.S. Pat. No. 2,992,670, wherein a minor proportion ofbromobutyl is blended with a major proportion of chlorobutyl in order toimprove the adhesion properties of chlorobutyl with high unsaturationrubber.

Another technique for improving the adhesion properties of chlorobutylwith high unsaturation rubber is disclosed in U.S. Pat. No. 2,933,117,which teaches that a chlorinated butyl inner lining of a tubeless tirecan be adhered to a carcass containing one or more high unsaturationrubbers by the introduction of an interposed layer containing anadmixture of a high unsaturation rubber and a brominated butyl rubber.

Still another technique for adhering chlorobutyl to a high unsaturationrubber is disclosed in U.S. Pat. No. 2,975,816, wherein a laminatedrubber structure was prepared which consisted of:

(1) AN INNER LINING OF CHLOROBUTYL AND A HIGH UNSATURATION RUBBERMODIFIED WITH CERTAIN N-bromo compounds;

(2) A CARCASS LAYER CONTAINING ONE OR MORE HIGH UNSATURATION RUBBERSMODIFIED WITH A N-bromo compound, and

(3) AN OUTER RUBBER LAYER CONTAINING AT LEAST ONE RUBBER POLYMER.

SUMMARY OF THE INVENTION

It has now surprisingly been found that the compatibility andcovulcanizability of chlorobutyl with a high unsaturation rubber can begreatly improved without the need for blending a chlorobutyl rubber witha bromobutyl rubber. Such an improvement is accomplished by the additionof certain bromine or iodine-containing compounds. These bromine oriodine-containing compounds can be either inorganic or organic. Ifinorganic, they are preferably in the form of a Lewis acid, e.g.,aluminum bromide. If organic, the bromine or iodine is preferably bondedto a carbon atom which in turn is bonded to one to three functionalgroups which are capable of stabilizing a positive charge at thebromine-bonded carbon. Illustrative of such groups are nitrile,carbonyl, aryl, vinyl, etc.

DETAILED DESCRIPTION

The expression "butyl rubber" as employed in this specification is wellknown in the art and is intended to include those copolymers made from apolymerization reaction mixture having therein from about 70 to about99.5% by weight of an isoolefin, which has about 4 to about 7 carbonatoms (e.g., isobutylene) and about 30 to about 0.5% by weight of aconjugated multiolefin having from about 4 to about 14 carbon atoms,e.g., isoprene. The resulting copolymer contains about 85 to about 99.5%by weight of combined isoolefin and about 0.5 to about 15% of combinedmultiolefin. The preparation of butyl rubber is well known in the art,and therefore a detailed description of its preparation is not includedin this specification. The preparation of butyl rubber is disclosed inU.S. Pat. No. 2,356,128 which is incorporated herein by reference.

The term "chlorobutyl" as used in the specification and claims means ahalogenated butyl rubber wherein the halogen is chlorine. Chlorobutylrubber is commercially available and may be prepared by chlorinatingbutyl rubber in a solution containing between 1 to 60% by weight ofbutyl rubber in a substantially inert C₅ -C₈ hydrocarbon solvent such aspentane, hexane, heptane, etc. and contacting this butyl rubber cementwith chlorine gas for about 2 secs. to about 25 mins. wherebychlorobutyl rubber and hydrogen halide are formed, the polymercontaining up to one or more halogen atoms per double bond initiallypresent in the polymer. The preparation of chlorobutyl rubber is old inthe art, see e.g. U.S. Pat. No. 3,099,644, which is incorporated hereinby reference. This invention is not intended to be limited in any way bythe manner in which butyl rubber is chlorinated.

In general any chlorobutyl rubber can be used. Illustrative of thechlorobutyl rubber used in this invention is a chlorinated butyl rubberwhich before chlorination analyzes 1.8 mole % unsaturation and aviscosity average molecular weight of about 450,000. The high molecularweight butyl rubber starting material contained from about 0.5 to about6% of combined diolefin.

The term "high unsaturation rubber" as used in the specification andclaims means those rubbers containing at least 30 mole % unsaturation.Illustrative of such rubbers are natural rubber, styrene-butadienerubber, polybutadiene, polyisoprene, and polychloroprene and mixturesthereof.

It will be evident to those skilled in the art that the scope of thisinvention includes other chlorinated low unsaturation rubbers whereinthe amount of unsaturation is less than 30 mole % and the viscosityaverage molecular weight is about 10,000 to 1,000,000. Illustrative ofsuch an elastomer would be chlorinated EPDM. Methods for preparingchlorinated EPDM are well known in the art; said EPDM may be prepared byreacting an EPDM consisting of ethylene, an alpha-olefin other thanethylene and a small amount of non-conjugated diolefin with achlorinated hydrocarbon such as carbon tetrachloride, chloroform,trichloroethylene, tetrachloroethylene or monochlorobenzene in thepresence or absence of a free radical initiator, e.g., UV light,chemical initiators, etc.

Illustrative of a chlorinated EPDM suitable for use in this invention isone having the following properties: ethylene content, 48 wt. %;ethylene norbornene content, 9 wt. %; a chlorine content of 0.65 wt. %and having an iodine number of 18.6 and a Mooney Viscosity ML 260 of 67.

Organic bromine and iodine compounds suitable for use in this inventionare preferably C₁ to C₃₀ and more preferably C₁ to C₂₀ compounds whereinthe bromine or iodine is bonded to a carbon atom which also has bondedthereto, two or three additional groups wherein at least one of thegroups is a functional group capable of stabilizing a positive charge atthe halogen-bonded carbon. Illustrative of groups capable of stabilizingsaid positive charge and suitable for use in this invention include (butare not limited to) nitrile, carboxyl, aryl, vinyl and carbonyl. Groupsother than the halogen and stabilizing groups which may also be attachedto the halogen-bonded carbon may be any of the non-electron withdrawinggroups. Illustrative of such groups suitable for use in this inventionare aliphatic groups, double bonded oxygen, hydrogen and an additionalbromine.

Illustrative of organic bromine-containing compounds suitable for use inthis invention include (but is not limited to) α-bromoacetophenone,bromodiphenylmethane, 9-bromofluorene, diethyl bromomalonate, benzoylbromide, cinnamyl bromide, 1,4-dibromo-2-butene, bromoacetic acid,1,4-dibromo-2,3-butanedione, diethyl dibromomalonate,dibromoacetonitrile, tribromoacetaldehyde, α-bromoisobutyrophenone,ethyl 2-bromoisobutyrate, α,α,α',α' tetrabromo σ-xylene and9,10-dibromoanthracene. Preferred are diethyl bromomalonate, bromoaceticacid and cinnamyl bromide.

Organic iodine-containing compounds which are suitable for use in thisinvention include (but are not limited to) α-iodoacetophenone,iodoacetic acid, cinnamyl iodide.

Also within the scope of this invention are organic compounds similar tothose above but which contain both iodine and bromine atoms.

It has also been found that certain types of bromine-containinginorganic compounds are suitable for use in this invention. Suchinorganic compounds are preferably Lewis acids such as aluminum bromideand zinc bromide. When an inorganic bromine-containing compound is usedwhich cannot be directly dispersed in the rubber blend because of thecompound's high melting point, it is preferred that such a brominecontaining compound be first dissolved in a suitable solvent before itsintroduction into the rubber blend. Illustrative of such suitablesolvents would be water and oxygenated hydrocarbons such as ethers,esters and alcohols. An example of such a solution would be a 33% byweight solution of zinc bromide in isopropanol.

An advantage of this invention is that it increases the utility ofchlorobutyl rubber so that it can be used in applications in whichbromobutyl rubber has been advantageous because of its more rapid cure.One such application would be in molded products such as pharmaceuticalstoppers. Often bromobutyl rubber as opposed to chlorobutyl rubber isused in the production of such stoppers to the fact that bromobutyl hasa faster cure rate than chlorobutyl thus leading to a higher productionrate. But by using bromobutyl rubber for such applications, anoccupational hazard may also be created in view of the fact that brominemay be introduced into the working environment. By means of thisinvention one is able to obtain as fast a cure rate with the brominemodified chlorobutyl as with bromobutyl. The occupational hazard createdby use of bromobutyl is also reduced owing to the fact that chlorobutyldehydrochlorinates at a much slower rate than bromobutyldehydrobrominates.

The compositions of this invention may be compounded by conventionalcompounding methods known in the art. In general the chlorinated lowunsaturation rubber and/or high unsaturation rubber is mixed in aconventional mixer, although a banbury mixer is preferred, at about 75°C. to about 250° C. for about 1 to about 10 minutes. More preferred is atemperature of about 100° C. to about 200° C. for about 3 to about 8minutes and most preferred is a temperature of about 150° C. for about 6minutes. The rubber composition is then milled with the bromine oriodine containing compound preferably at a temperature of about 0° C. toabout 100° C. for a time long enough to completely mix the composition.More preferred is a temperature of about 20° C. to about 50° C. forabout 1 to about 5 minutes.

The amount of bromine or iodine containing compound required will varywith the amount of chlorobutyl rubber. Preferably enough bromine oriodine containing compound is used so as to provide from about 0.125moles of bromine or iodine to about 1 mole of bromine or iodine per moleof chlorine present in the chlorobutyl rubber. More preferred is about0.250 moles to about 0.500 moles of bromine or iodine present per moleof chlorine.

It will also be evident to those skilled in the art that conventionalrubber compounding materials may be used in the practice of thisinvention. Illustrative of such conventional compounding materialssuitable for use in this invention would be fillers, oils, accelerators,etc.

Also within the scope of this invention is a method of improving theadhesion of chlorinated low unsaturated rubbers to high unsaturatedrubbers wherein the interfacial surfaces of said rubbers are treatedwith a bromine or iodine containing composition. The bromine or iodinecontaining compounds are those previously described and may be appliedin solution, paste or other appropriate means.

This invention will be more fully illustrated by the following examples.

EXAMPLE 1

Both chlorobutyl rubber and natural rubber were each compounded withfillers and plasticizers in a Banbury for 6 minutes at 149° C. Thecompounds were then transferred to a rubber mill wherein zinc oxide,sulfur and accelerators were added and milled. The materials were thenpress cured for 30 minutes at 153° C. Formulation data is found inTables I and II below.

The chlorobutyl compound was tested by conventional means for %elongation, tensile strength and 300% modulus; the results are found atthe end of Table I.

The two rubber compounds were adhered together and a strip adhesion test(ASTM D413-38) was performed; the results are listed in Table III below.

                  TABLE I                                                         ______________________________________                                        Chlorobutyl Rubber Compound                                                                         Parts per Hundred                                       ______________________________________                                        Chlorobutyl           100.0                                                   Regal 300 (HAF Block) 25.0                                                    MT (Medium Thermal Furnace Block)                                                                   75.0                                                    Stearic Acid          1.0                                                     Amberol ST 137 × (1)                                                                          4.0                                                     Flexon 840 oil (Plasticizer)                                                                        6.0                                                     Sunolite 127 Wax      2.0                                                     Zinc Oxide            5.0                                                     Sulfur                1.5                                                     Mercaptobenzothiazyl disulfide (MBTS)                                                               1.0                                                     Properties                                                                    300% Modulus, psi     800.0                                                   Tensile Strength, psi 1300.0                                                  Elongation, %         550.0                                                   Mooney Scorch at 132°  C. (minutes                                     to 10 point rise)     10.2                                                    ______________________________________                                         (1) phenol-formaldehyde resin                                            

                  TABLE II                                                        ______________________________________                                        Natural Rubber Blend  Parts per Hundred                                       ______________________________________                                        RSS No.1 (1)          100.0                                                   SRF Black             50.0                                                    Flexon 580 oil (Plasticizer)                                                                        5.0                                                     BLE-25 (2)            1.5                                                     Stearic Acid          1.5                                                     Zinc Oxide            5.0                                                     Santocure (3)         1.2                                                     Tetramethyl thiuram disulfide (TMTDS)                                                               0.1                                                     Sulfur                2.5                                                     ______________________________________                                         (1) Ribbed smoked sheet - natural rubber                                      (2) High temperature reaction product of diphenylamino and acetone            (3) N-cyclohexyl-2-benzo thiazolesulfenamide                             

                  TABLE III                                                       ______________________________________                                        Adhesion of Chlorobutyl to Natural Rubber Blend                               ______________________________________                                        lbs/inch at 24° C.                                                                       48 Interfacial separation                                   lbs/inch at 121° C.                                                                       5 Interfacial separation                                   ______________________________________                                    

The above data illustrates the non-compatibility of chlorobutyl with anatural rubber blend. In view of the poor adhesion qualities ofchlorobutyl with natural rubber, such a combination would beunacceptable for such uses as high performance tire construction.

EXAMPLES 2-9

A chlorobutyl rubber composition was prepared as in Example 1 exceptthat bromine-containing compounds were introduced during the millingstage. The bromine-containing chlorobutyl was adhered to the naturalrubber formulation of Example 1 and ASTM D413-38 strip-adhesion testswere performed. The following is a table illustrating some of thebromine-containing compounds suitable for use in this invention andtheir ability to enhance the compatibility of chlorobutyl with highunsaturated rubber compositions.

                                      TABLE IV                                    __________________________________________________________________________    Effects of Selected Bromine-Containing Compounds                              on the Compatability of Chlorobutyl with Natural                              Rubber                                                                        __________________________________________________________________________                     Mole of                                                                             300% Tensile                                                            Br to Modulus                                                                            Strength                                                                           Elonga-                                                                           Adhesion to                                                                           Adhesion to                                                                            Mooney Scorch           Ex.  Bromine Compound                                                                          Mole of Cl                                                                          psi  psi  tion %                                                                            NR at 24° C.                                                                   NR at 121° C.                                                                   at 132° C.                                                             (2)                     __________________________________________________________________________    2  1,4-dibromo-2,3-butanedione                                                                  0.5  950  1100 350 52T     38T      2.6                                       0.25 1000 1250 400 70I     43T      3.8                                       0.125                                                                              1000 1300 450 90T     9I       5.0                     3  Diethyl Bromomalonate                                                                        0.5  550  1000 600 120T    68T      6.6                                       0.25 700  1100 600 170T    80T      7.1                                       0.125                                                                              780  1200 500 70I,T   4-I      6.4                     4  α-bromoacetophenone                                                                    0.5  650  1000 600 165T    75T      5.4                                       0.25 850  1200 550 125T    80T      6.2                                       0.125                                                                              880  1250 500 80I,T   9-I      7.0                     5  Bromoacetic Acid                                                                             0.5  750  1000 500 118T    65T      4.8                                       0.25 850  1100 550 90I     58T      5.2                                       0.125                                                                              930  1200 500 73T     4I       7.8                     6  Cinnamyl bromide                                                                             0.5  900  1150 400 105T    50T      1.7                                       0.25 950  1300 530 75I     50T      4.8                                       0.125                                                                              930  1330 400 90I,T   13I,T    4.8                     7  1,4-dibromo-2-butene                                                                         0.5  1000 1250 450 82T     60T      7.0                                       0.25 900  1200 500 120T    38T      9.4                                       0.125                                                                              1000 1330 500 44I     7I       8.4                     8  Zinc bromide(1)                                                                              0.5  1200 1350 400 --      --       <2.0                                      0.25 1050 1300 450 130-T   50-T     2.0                                       0.125                                                                              880  1380 500 95I,T   6-I      5.8                     9  Aluminum Bromide                                                                             0.5  950  1250 450 105T    60T      2.0                     __________________________________________________________________________     (1) dissolved in isopropanol to give a 33% by weight solution; (2) minute     to 10 point rise                                                              I = Interfacial separation (not desirable)                                    T = Stock Tearing (desirable)                                            

The above table shows that the compatibility of chlorobutyl with highunsaturation rubber compositions can be increased with the use ofselected bromine-containing organic and inorganic compounds. The abovetable also illustrates that as the mole ratio of bromine to chlorine inthe chlorobutyl is decreased, the adhesion property ofbromine-containing chlorobutyl to natural rubber decreases. As shownabove, it is preferred that the mole ratio of bromine to chlorine notfall substantially below 0.125 mole of bromine per mole of chlorine.

Also indicated by this table is the fact that the addition ofbromine-containing compounds to chlorobutyl significantly decreases theMooney Scorch time. This shows that the addition of thesebromine-containing compounds gives a faster cure rate than chlorobutylalone.

EXAMPLE 10

Rubber compositions were prepared according to Example 2 except that aniodine-containing compound as opposed to a bromine-containing compoundwas reacted with the chlorobutyl during milling. The following is atable illustrating the suitability of one such iodine compound for usein the present invention.

                  TABLE V                                                         ______________________________________                                        Effect of Iodoacetic Acid on the Compatibility                                of Chlorobutyl with Natural Rubber                                            0.25 Moles of Iodine per Mole of Chlorine                                     ______________________________________                                        300%   Tensile            Adhesion to                                                                            Adhesion to                                Modulus                                                                              Strength Elongation                                                                              NR at 24° C.                                                                    NR at 121° C.                       psi    psi      %         lbs/inch lbs/inch                                   ______________________________________                                        750    1200     500       65-T     25-T                                       ______________________________________                                         T = stock tearing                                                        

EXAMPLE 11

A vulcanizate of chlorobutyl/natural rubber was prepared according tothe procedure of Example 1. The formulation for such a rubber blend isfound in Table VI. Tensile strength and dynamic stability of this rubberblend were measured by conventional means, and the data set forth inTable VII below.

                  TABLE VI                                                        ______________________________________                                        Formulation of Chlorobutyl/Natural Rubber Vulcanizate                         ______________________________________                                                            Parts per Hundred                                         ______________________________________                                        Chlorobutyl           50.0                                                    RSS No.1 (natural rubber)                                                                           50.0                                                    HAF Black             35.0                                                    Circosol 4240 oil     5.0                                                     Age Rite Stalite (1)  1.0                                                     Stearic Acid          1.5                                                     ZnO                   5.0                                                     Sulfur                1.5                                                     MBTS                  1.0                                                     ______________________________________                                         Press cured for 30 minutes at 153° C.                                  (1) Mixture of alkylated diphenylamines                                  

                  TABLE VII                                                       ______________________________________                                        Tensile Strength and Dynamic Stability of Chlorobutyl/                        Natural Rubber Vulcanizate                                                    ______________________________________                                        300% Modulus, psi       990                                                   Tensile Strength, psi   1850                                                  Elongation %            500                                                   Kilocycles to rupture.sup.1                                                                           31                                                    ______________________________________                                         .sup.1 Monsanto fatigue-to-fatigue test at a nominal 140% extension.     

EXAMPLES 12-19

Chlorobutyl/natural rubber compositions of Example 11 were preparedexcept that certain bromine-containing compounds were introduced duringthe milling stage. After curing, tensile strength and dynamic stabilitydata were obtained by conventional means, and the data for thesebromine-containing compositions are found in Table VIII below.

                                      TABLE VIII                                  __________________________________________________________________________    Effect of Selected Bromine Containing Compounds                               on Tensile Strength and Dynamic Stability of                                  Chlorobutyl/Natural Rubber Blend                                              __________________________________________________________________________                                       Tensile                                                       Moles of Br to                                                                         300%   Strength                                                                           Elongation                                                                          Kilocycles to                   Ex.  Bromine Compound                                                                            Moles of Cl                                                                            Modulus, psi                                                                         psi  %     Rupture                         __________________________________________________________________________    12 1,4-dibromo-2,3-butanedione                                                                     0.50   850    2250 550   71                                                   0.25   1100   2400 550   57                                                   0.125  1000   2000 500   49                              13 Diethyl Bromomalonate                                                                           0.50   900    2550 650   121                                                  0.25   1000   2700 600   57                                                   0.125  950    2050 500   47                              14 α-bromoacetophenone                                                                       0.50   600    2500 650   202                                                  0.25   950    2500 600   45                                                   0.125  800    2250 600   47                              15 Bromoacetic Acid  0.50   500    2350 700   206                                                  0.25   1050   2500 570   55                                                   0.125  1000   2350 550   50                              16 Cinnamyl Bromide  0.50   850    2750 650   74                                                   0.25   950    2500 500   53                                                   0.125  830    2000 500   55                              17 1,4-dibromo-2-butene                                                                            0.50   900    2500 600   88                                                   0.25   1100   2400 550   50                                                   0.125  930    1880 500   27                              18 Zinc Bromide (1)  0.50   1100   2700 550   49                                                   0.25   1200   2550 500   46                                                   0.125  1000   2180 550   46                              19 Aluminum Bromide  0.50   1000   2550 550   60                              __________________________________________________________________________     (1) dissolved in isopropanol to give a 33% by weight solution            

The above table shows that tensile strength and dynamic stability of ablend of chlorobutyl with natural rubber is improved by the addition ofthe bromine-containing compounds of this invention. It is also apparentfrom this data that as the mole % of bromine to chlorine decreases, thecompatibility of chlorobutyl to natural rubber decreases.

EXAMPLE 20

A vulcanizate of claim 11 was prepared, except an iodine-containingcompound was added to the composition during the milling stage. Therubber composition was also cured for 30 minutes at 153° C. Thefollowing table shows the ability of an iodine compound of thisinvention to increase the compatibility of chlorobutyl to natural rubber

                  TABLE IX                                                        ______________________________________                                        Effect on Tensile Strength and Dynamic Stability                              by Addition of Iodoacetic Acid in Chlorobutyl/ -Natural Rubber                ______________________________________                                        Blends                                                                        Moles of                                                                      Iodine    300%     Tensile           Kilo-                                    per mole  Modulus, Strength,  Elonga-                                                                              cycles to                                of Chlorine                                                                             psi      psi        tion % Rupture                                  ______________________________________                                        0.25      930      2450       550    64                                       ______________________________________                                    

It is to be understood that this invention is not restricted to theforegoing examples which serve only to illustrate the present invention.Numerous variations may be devised without departing from the scope ofthis invention.

What is claimed is:
 1. A laminated composition of matter comprising onelayer of chlorobutyl rubber and a halogen-containing organic compound,wherein the halogen is bonded to a carbon atom which is in turn bondedto 1 to 3 functional groups capable of stabilizing the positive chargeat the halogen-carbon bond, and wherein the halogen is selected from thegroup consisting of bromine and iodine; and another layer comprising ahigh unsaturation rubber wherein the unsaturation is at least 30 mole %.2. The composition of claim 1 wherein the halogen-containing compound isselected from the group consisting of diethylbromomalonate,α-bromoacetophenone, bromoacetic acid, cinnamyl bromide,1,4-dibromo-2-butene and iodoacetic acid.
 3. The composition of claim 1wherein said composition contains at least 0.125 moles of halogen permole of chlorine.
 4. The composition of claim 1 wherein the functionalgroup is selected from the group consisting of nitrile, carboxyl, aryl,vinyl, and carbonyl.
 5. The composition of claim 1 wherein the highunsaturated rubber is selected from the group consisting of naturalrubber, styrene butadiene rubber, polybutadiene, polyisoprene,polychloroprene, and mixtures thereof.